The field of catalytic cracking and particularly dense or dilute fluid phase catalytic operations have been undergoing progressive development since early 1940. Thus as new experience was gained in operating and design parameters, new catalyst compositions were developed which required a further refinement of known operating and design parameters so as to extract maximum efficiency from the combination operation. With the advent of high activity crystalline zeolite cracking catalyst development, we once again find ourselves in a new area of operation requiring ever further refinements in order to take advantage of the new catalyst activity, selectivity and operating sensitivity. The present invention is concerned with a combination operation which relies upon a combination of catalyst functions mutually contributing to accomplish upgrading of available refinery feed material.